| With the continuous advancement of modern industry,there are more and more kinds of lubricating oils required for mechanical equipment.In order to improve the friction performance of lubricating oil,it is necessary to improve the lubricating oil.It is effective to add nanoparticle additives to the liquid lubricant.the way.Molybdenum disulfide is a natural lubricant widely used as a solid lubricant and lubricant additive.Compared with ordinary molybdenum disulfide,nano molybdenum disulfide has more excellent lubricating properties as a lubricating oil additive.In this paper,a molybdenum disulfide precursor solution was synthesized by using sodium molybdate and thiourea,and the eutectic point of the precursor solution was measured.Then,the solution pH,reaction temperature,additive type,and lyophilization method were used under different process parameters.The nano-molybdenum disulfide was prepared by orthogonal experiment in the freezing mode.The morphology and particle size of the samples were examined by electron microscopy.The quality of the molybdenum disulfide powder was discussed.The results of transmission electron microscopy showed that the nano-sized molybdenum disulfide particles obtained by lyophilization were spherical and uniformly distributed,and the particle size was about 100 nm.The optimum process parameters for the freeze-drying of molybdenum disulfide by experimental data are pH value of the solution 2.The additive is CTAB,the reaction temperature is 160?,and the freezing method is vacuum freezing.Further,the atomic force microscope was used to observe the sample with the smallest particle size.The AFM three-dimensional topography showed that the sample had a small amount of agglomeration,the maximum height of the agglomeration was not more than 100 nm,and the minimum particle size of no agglomeration was between 25 and 32 nm.Aiming at the problem that the vacuum freezing process is difficult to control,this paper studies the heat and mass transfer mechanism of solution vacuum freezing process,establishes the kinetic model of solution temperature and pressure change during vacuum freezing process and the temperature and mass change of solution during vacuum freezing process.Thermodynamic model.The model is solved and the relationship between mass,temperature and pressure as a function of time is obtained.The relationship between pressure and temperature with time is basically consistent with the trend of the actual experimental curve,which verifies the rationality of the model.It laid a certain theoretical foundation for the promotion and application of vacuum freezing.In this paper,the effects of freeze-dried nanometer molybdenum disulfide on the friction properties of base oil were studied by four-ball friction tester and lubricating oil anti-wear tester.The friction coefficient and antifriction effect of the lubricating oil with freeze-dried nano molybdenum disulfide were studied by using a four-ball friction tester.The experimental results show that after the addition of nano molybdenum disulfide to the base oil,the size of the wear spot is reduced by the four-ball friction tester 12%,the friction coefficient decreased by 6.5%,indicating that nano-molybdenum disulfide as a lubricating oil additive exhibited a lower friction coefficient and better anti-wearing effect under load conditions.The extreme pressure performance of nano-molybdenum disulfide as a lubricating oil additive was studied using a lubricating oil anti-wear tester.The experimental results show that when the amount of nanomolybdenum disulfide added is 0.006%,the PB value of the lubricating oil anti-wear test machine reaches the maximum 700kg,which is 72%higher than the base oil sample.When the addition amount of nanometer molybdenum disulfide is 0.004%,the wear scar area of the anti-wear machine is the smallest,which is 87%lower than that of the non-added nano molybdenum disulfide.Compared with the base oil,the friction performance of the nano molybdenum disulfide base oil is added.It has been improved. |
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